Break in speed for new Prius

I think it's in the front of the Passport maintenance manual, not sure. In essence, don't drive like a jerk for at least 600 miles, no jackrabbit starts, no testing the ABS unless you need to. Since the computer controls when and how fast the Internal Combustion Engine runs, you don't have to baby your new baby, just treat her nice. Try to stay under 70 mph for the first 600 miles. Your MPG will be better that way too, but don't worry about getting super MPG for a while. Just drive and enjoy, learn your car.

And welcome to PriusChat, GB!

 

Take it from me, I was an ASE certified mechanic, and have tons of experience working on engines. The break-in period for a new engine is 500 miles, that is to seat the rings to the cylinder walls, and nothing else. From what I have gathered so far with the Prius is the break in period is just a bit longer, 600 is correct, but the engine doesnt rev as high as a normal engine, so driving up to 70 is OK, dont exceed it for at least 1000 miles. DO NOT under ANY circumstances maintain a steady speed, vary it a LOT. THis is what helps seat the rings. Basically, when I rebuilt an engine, (Havent touched one in years, bad back) after it was installed and tuned up, pressure checked and OK for the road, I would take it out on a long strecth of empty road, gun it to 50-60 MPH then coast. I would do that 10 times to seat the rings. Once that is done, then no heavy accelerations for the first 500 miles and alway vary the speed. I am not sure how the factory does it, but they seat the rings in a similiar fashion. After the initial 600-1000 miles, drive it like you stole it. Unlike engines of yesteryear, todays engines have very high tolerences, machining is damn near perfect, and variances are practically nil. This is mainly why you no longer need to change out the oil after break-in like with a rebuild, or earlier cars. Alos, factory oil tends to have special modifiers in them to help ensure a clean break-in period, not neccesarily the oil itself, but the lubricants that were used during the build of the engine, like moly prelube, graphite, lubes of that nature.

If you ever have a chance to see a brand new engine being made, do it, it is interesting to see how they are made, majority of it is done by robotics now.

 

Hi All,

The Prius HSD will vary the engine RPM, and use electric assist automatically, even at a constant speed, as long as there is some variablity in the driving conditions. All this variability needs to be is a slight upgrade, or downgrade, passing trucks , shifting winds, overpasses blocking, or aiding the wind.

So, unless your in a windless salt-pan deasert, or eastern Oklahoma (dead flat!), your probably OK to run at a constant speed (NOT Constant RPM) with the Prius during break-in.

 

<div class='quotetop'>QUOTE(Bill Merchant @ Apr 22 2007, 11:56 PM) [snapback]428213[/snapback]</div>

 

Not to sound like a newb or anything, but what'll happen if you break it in wrong?

 

<div class='quotetop'>QUOTE(Alexstarfire @ Apr 24 2007, 01:51 AM) [snapback]428886[/snapback]</div>

It is a bit difficult to improperly breakin a new engine in todays cars, but what can happen is if you over rev the engine, you can cause the rings to break, sieze, score the cylinder walls, crack a piston, etc. The engine will not seal properly and it will burn oil. Bearings, guides, seals etc dont need a break in period, camshafts/lifters OTOH do. The area that the lifter rides against the cam will need to wear in a bit, but the main item that requires break in are the rings, it takes a while for them to wear sufficiently to the point where they sit against the cylinder walls and give the strongest seal. Rings flex with the up down motion of the piston and need to wear the edges smooth so they seat. Those are really the only engine parts that move in such a manner, the rest basically dont move, but have a thin layer of oil seperating them from each other.

BTW, one other poster mentioned the PCM controls the engine speed, this may be true, but not enough to properly break in the engine. Variance in speed means good acceleration/deceleration, which the Prius wont do by itself, the variance is not enough. varying speed between 45-55 Mph is what will do it properly.

 

Stomping on the brakes before they are worn in might cause the disks to warp. Drive easy the first 600 miles, just like it says in the owner's manual, and you'll be fine.

 

Bill Merchant is correct. ACD is talking about conventional cars, where there is a fixed ratio, for any given gear, between engine RPM and vehicle speed. There is no such fixed ratio in the Prius. Richard is correct about the brakes.

Read the owner's manual and do as it says.

 

Former comments are right. Look at page 318 Owner's Manual.

 

Stomping on brakes doesnt warp them. In fact most "warped" rotors are actually still true. They have Cementite build up on them that causes the pulsing when you step on the brakes. Brakes properly bedded dont need miles to "break" in. You can bed the pads in just a few miles of driving, and when done properly work best. Run up to 60 MPH, then firmly stop the car, braking almost to lock up, then accelerate up to 60 again, and repeat until You feel a noticeable fade. Then park the car to let the rotors and pads cool off. This is all that needs to be done to properly seat the pads.

What causes "warpage" is when heating up the pads, by either riding the brakes, or stopping hard all the time and then keeping the pads pressed against the rotors. This causes a build up of material transferred between the pad and rotor and when you start rolling again, this build up hardens on the rotor causing the pulsations.

In Hybrids though, you rarely use service brakes unless you don't know how to drive the car, and they last 3-4 times as long as in a normal car.

It takes a LOT to truly warp a rotor. You have to get them smoking hot then quench them with cold water, and even then they may not actually warp. I have done at least 1000 or more brake jobs when I turned a wrench and rarely ever encountered an actual warped disk. Most of the actual warped ones were right out of the box brand new. I would say 98% of "warped" disks were just overheated with high spots, and one some you could see the outline of the pad after the first pass.


BTW even in a Hybrid, you still have to be easy on acceleration during break in. It actually takes longer to fully break in a Hybrid engine than in a conventional car due to the low RPM they run at, but they will also last much longer than conventional cars due to the low RPM's.

 

Unfortunately taking the car up to sixty and braking will not bed the brakes on the Prius. Again rather like the transmission the Prius braking system is very different from most other cars in that it uses regen braking. To achieve the affect Acdii talked about accelerate to 50 mph (no more if you want the transmission to stay in one piece) select neutral then brake. This forces the Prius to use the friction brakes "rotors and pads" and not regen.

John (Britprius)

 

All this talk about not beating on the ICE of a brand new car (Prius notwithstanding) makes me wonder... how come all the new cars that the dealerships let people test drive and beat on, dont have seized/damaged engines?

I havent heard of any engine break-in problems since like 1982.

 

I assume they are the one where the owner is wondering how much oil burning is normal at 100,000 miles.

 

Speaking of things that you haven't heard from in years...has somebody been digging in the cemetery for old threads???

It's difficult to break an OEM engine, or break one in wrong. You can put a brick on your accelerator pedal...go in for a cup of coffee, and come back out, remove the brick and your motor will be juuuuust fine.
The reason that you always see threads like this one is that people really REALLY REALLY love their Priuses and they're terrified that other people's cars will grow up to be more successful than their cars, and so they spoil them.

It's not nuclear physics folks.
They use Priuses in rental car fleets, and some of the larger corporations (like mine!) use Priuses as a $25,000 rolling billboard so that the eco-weenies will think that they REALLY care about the environment.
I'll bet you my CPO coin that Hertz, Avis, Budget, Dollar, and Rent-a-Heap, Cheap all use the same basic break-in philosophy that my company uses.
I call it "Break-in Lite 1.0", and it goes something like this:
1. Give Technician or customer Key(fob)
2. Tell them where the car is.
3. Have them sign paperwork.
4. Advise them to have a nice day. (optional v1.01 and higher only)

That's it.
That's all.
The reason that I would never EVER consider buying a fleet or former rental car lies in the fact that their drivers often beat the living crap out of them, and then they are not-so-lovingly [sic] maintained by large corporations that are operting on a razor thin profit margin.
Hey MAN!!!
Those friggin filters and fluids cost MONEY!!!!
.....just gun-deck the PM's and sell the car off after the warranty expires!

Break-in?
Don't worry about it.
If you get to 2,000 miles and your car isn't smoking or glugging a quart of oil every tank of gas????
You broke it in right!